In: Statistics and Probability
If n=210 and ˆp(p-hat) =0.4, find the margin of error at a 95%
confidence level
Give your answer to three decimals
Solution :
Given that,
n = 210
Point estimate = sample proportion = =0.4
1 - = 1-0.4 =0.6
At 95% confidence level the z is ,
= 1 - 95% = 1 - 0.95 = 0.05
/ 2 = 0.05 / 2 = 0.025
Z/2 = Z0.025 = 1.96 ( Using z table )
Margin of error = E = Z/2 * ((( * (1 - )) / n)
= 1.96 (((0.4*0.6) / 210)
E = 0.066